Photographic process



July 28, 1964 FIG. I

FIG. 2

E. H. LAND 3,142,566

PHOTOGRAPHIC PROCESS T Original Filed May 7, 1958 TT TTTTTT VacuumDeposlfion of Gold TTTTTTT Vacuum DcposH'ion of Silvcr 26{Pho-Tosensil'iva S+ra+um T T T T T T T T Halogen Vapor --maezzez4a{zzgjf 'zz Heal' 1N NTOR.

BYZ M M Jun AT TO R N E YS United States Patent Continuation ofapplication Ser. No. 733,754, May 7,

1958. This application Feb. 14, 1962, Ser. No. 176,844 7 Claims. (Cl.96-61) The present invention relates to novel photographic processes,and more particularly to novel processes for developing latent imagesformed in photoexposed photosensitive elements.

The primary object of the present invention is the novel use ofphotographic elements comprising photosensitive materials formed, atleast in part, by the vacuum deposition of their components upon theirsupport. It has been found that such extremely thin andprotective-colloid-free photosensitive materials possess peculiarcharacteristics that unexpectedly make feasible the development oflatent images by the application of heat.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The invention accordingly comprises the process possessing the severalsteps and the relation and order of one or more of such steps withrespect to each of the others, which are exemplified in the followingdetailed disclosure, and the scope of the application of which will beindicated in the claims.

For a fuller understanding of the nature and objects of the presentinvention, reference should be had to the following detailed descriptiontaken in connection with the accompanying drawing wherein:

FIGURE 1 shows succcessive, exaggerated diagrammatic cross-sectionalviews of materials being treated in accordance with the presentinvention; and

FIGURE 2 shows successive, exaggerated cross-sectional views of theproduct of the process of FIGURE 1 being used in accordance with thepresent invention.

Generally, the process of the present invention herein disclosed isbased upon the production of a photosensitive stratum by vacuumdepositing at least a metal of a photosensitive salt on a support andthen subjecting the metal on the support to halogen vapor. The support,for example, is composed of a suitable plastic such as hydrolyzedcellulose acetate or a suitable paper such as baryta paper.

The step of vacuum depositing involves either evaporating or sputteringat pressures below one hundred microns of mercury, and usually withinthe range of from 0.1 to 100 microns of mercury, these pressures beingproduced by continuous evacuation to ensure the rapid removal of anygases produced during the vacuum deposition process. The metallicdistribution of the stratum initially formed preferably is in sufficientconcentration per unit area to give rise to an optical transmission ofat most 40%. Unusually satisfactory results are achieved when the metaldistribution includes both gold and silver deposited in either sequenceor together. Best results are achieved when the silver is vacuumdeposited in a concentration that by itself would give rise to anoptical transmission of from 10% to 30%, the gold is deposited in aconcentration that by itself would give rise to an optical transmissionof from 10% to 30% and the gold and silver are deposited inconcentrations which together give rise to an optical transmission offrom 0.01% to 1.0%.

Halogenation is eifected by subjecting the metallic stratum produced inthe foregoing way to the vapor of elemental halogen, e.g. chlorine,bromine, iodine or combinations thereof or to volatile halogen salts,e.g. hydrogen bromide, hydrogen iodide or combinations thereof at asuitable temperature, for example, room temperature.

Patented July 28, 1964 The metallic stratum, preferably, is subjected tothe halogen vapor for a period sufficient to effect substantiallycomplete halogenation, a condition that is indicated when the opticaltransmission of the stratum has increased substantially to between andIn accordance with the present invention, development of a latent imagein a photosensitive stratum produced in the foregoing way, by virtue ofits peculiar structure, is

effected by the application of heat, for example, the generation, byinfrared or ultra high frequency radiation, of temperatures elevatedabove room temperature for periods necessary to effect development.

Example FIGURE 1 illustrates the production of a photosensitive elementin accordance with the present invention. As shown, the support is ahydrolyzed cellulose acetate sheet 20, approximately 1 millimeter thick,3 inches wide and 6 /2 inches long. First, 5 milligrams of gold isevaporated uniformly onto the support to form a gold stratum 22. Theresulting optical transmission of the strip is 20%. Then 5 milligrams ofsilver is evaporated onto the support to form a gold-and-silver stratum24. The resulting optical transmission is 0.06%. Finally, goldand-silverstratum 24 is subjected in a closed jar to the vapor of a quantity ofhydrogen bromide until an optically clear photosensitive stratum 26 isformed. Photosensitive stratum 26 is characterized by low photographicspeed, negligible graininess and a long soft curve. The photosensitiveelement of FIGURE 1, after being photoexposed, is subjected to atemperature of approximately 100 F. A negative print of delicategradation is produced in approximately fifteen minutes. The print of theabove example may be fixed by reacting its unreduced silver with afixing vapor, e.g. hydrogen sulfide, to form a stable silver salt.

This application is a continuation of my application Serial No. 733,754,filed May 7, 1958.

Since certain changes may be made in the above process without departingfrom the scope of the invention herein involved, it is intended that allmatter contained in the above description and shown in the accompanyingdrawing shall be interpreted as illustrative and not in a limitingsense.

What is claimed is:

1. A process of forming photographic negative images comprising thesteps of (a) forming a photosensitive, vacuum deposited metallic halidestratum including at least silver halide, by vacuum depositing saidmetals, including silver, upon a support in a concentration providing ametallic stratum having an optical transmission of from about 0.01% toabout 1.0%, halogenating said vacuum deposited metallic stratum bycontacting said metallic stratum with halogen vapors provided with amember of the group consisting of elemental chlorine, elemental bromine,elemental iodine, and volatile salts of said elemental halogens for atime sufiicient to provide a halogenated metallic coating having anoptical transmission of from about 85% to about 100%, (b) photoexposingthe thusprepared photosensitive vacuum deposited metallic halidestratum, and (0) developing said exposed photosensitive vacuum depositedmetalic halide stratum to a visible negative image by subjecting saidstratum to heat above room temperature, said application of heat beingthe sole means of effecting said development.

2. The process of claim 1, wherein said metallic stratum includes goldand silver, each of said gold and silver being deposited in aconcentration which by itself would provide an optical transmisison offrom about 10% to about 30%, said coating of gold and silver togetherhaving a total optical transmisison of from about 0.01% to about 1.0%.

3 3. The process of'claim 1, wherein said exposed photosensitive vacuumdeposited metallic halide stratum is subjected to a temperature ofapproximately 100 F. for a time suflicient to develop said negativeimage.

4. The process of claim 2, wherein said photosensitive 5 metallic halidestratum consists of vacuum deposited silver and gold halogenated by theapplication of iodine vapors.

5. The process of claim 2, wherein said photosensitive metallic halidestratum consists of vacuum deposited silver and gold halogenated by theapplication of hydrogen bromide vapors.

6. The process of claim 1, including the step, after said heatdevelopment, of converting unexposed and undeveloped silver halide to alight stable silver salt.

7. The process of claim 1, including the step, after 4 said heatdevelopment, of reacting unexposed and undeveloped silver halide withhydrogen sulfide vapors.

References Cited in the file of this patent UNITED STATES PATENTS2,153,628 Knoll April 11, 1939 2,239,452 Williams Apr. 22, 19412,439,983 Morgan et al Apr. 20, 1948 OTHER REFERENCES Yamada et al.:Chem. Abstracts, vol. 50, pp. 11147-8. (Copy in Sci. Lib.)

Glafkides: Photographic Chemistry, I, Fountain Press, London 1958, p.319.

Humphrey: American Handbook of the Daguerreotype, 5th ed., pub. by S. D.Humphrey, N.Y., 1958, pp. 35-37, 158 and 159. (Copy in Sci. Lib.)

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.$142,566 July 28V 1964 Edwin H. Land It is hereby certifiedv that errorappears in the above numbered patent requiring correction and that thesaid Letters Patent should read as I corrected below.

Column 2 line 54, for "with'K second occurrence read by lines 69 and 71for "transmisison" each occurrence read transmission Signed and sealedthis 12th day of January 1965 (SEAL) Attest:

ERNEST W. SWIDER EDWARD J. BRENNER Attesting Officer 7 Commissioner ofPatents

1. A PROCESS OF FORMING PHOTOGRAPHIC NEGATIVE IMAGES COMPRISING THESTEPS OF (A) FORMING A PHOTOSENSITIVE, VACUUM DEPOSITED METALLIC HALIDESTRATUM INCLUDING AT LEAST SILVER HALIDE, BY VACUUM DEPOSITING SAIDMETALS, INCLUDING SILVER, UPON A SUPPORT IN A CONCENTRATION PROVIDING AMETALLIC STRATUM HAVING AN OPTICAL TRANSMISSION OF FROM ABOUT 0.01% TOABOUT 1.0%, HALOGENATING SAID VACUUM DEPOSITED METALLIC STRATUM BYCONTACTING SAID METALLIC STRATUM WITH HALOGEN VAPORS PROVIDED WITH AMEMBER OF THE GROUP CONSISTING OF ELEMENTAL CHLORINE, ELEMENTAL BROMINE,ELEMENTAL IODINE, AND VOLATILE SALTS OF SAID ELEMENTAL HALOGENS FOR ATIME SUFFICIENT TO PROVIDE A HALOGENATED